Legacy implementations of white LED light sources have been constructed by encircling an array of blue LED die with a reflective white dam and filling the area inside the dam with a silicone-phosphor mix. This legacy approach results in the blue LED die being surrounded by luminescent-materials-containing silicone, yet the resulting legacy implementations exhibit several significant drawbacks. First, light emitted by the luminescent materials that are located far from the LED die is scattered many times before being able to exit the structure. In the process of doing so, this light can be absorbed by other luminescent-material particles, adjacent LED die (if any), and/or by the materials that form the base of the structure (i.e., submount materials). While the reflectivity of the submount materials have been specially treated, for example, by coating the submount surface with either a high-reflectivity white coating or with highly-reflective metals such as silver, some fraction of the light is converted to heat, and the efficiency of light emission is reduced. A more desirable optical configuration is to fabricate such light sources with luminescent-materials particles juxtaposed in a spatial region very near the LED die themselves. In this manner, light scattering by luminescent-material particles far from the die and absorption by the submount materials can be reduced, and the efficiency of such a light source can be improved. For example, to conformally coat the die with a phosphor material a laminar sheet of silicone or other binder, which is impregnated with phosphors, is hot-rolled onto the LED die. This method has the disadvantage that there is poor coverage on the sides of the LED die, which result in reduced light output.
However, in order to have the luminescent materials particles confined to a spatial region very near the LED die themselves, what is needed is an inexpensive method of applying one or more conformal layers (e.g., coatings) of luminescent materials around LED die in order to improve the light emission efficiency of the LED light source while concurrently providing for desired color balance as well as reliable operation under high current density operation.